2,4-Dichlorophenol (2,4-DCP) is a feedstock chemical primarily used to produce
the herbicide 2,4-dichloropheoxyacetic acid (2,4-D). In October 1998, the
U.S. Environmental Protection Agency (EPA) was notified of the death of a worker
acutely exposed to 2,4-DCP. Follow-up investigation by EPA, the Occupational Safety
and Health Administration (OSHA), and CDC's National Institute for Occupational
Safety and Health (NIOSH) identified four earlier deaths associated with acute
2,4-DCP exposure, which occurred during 1980--1992. All of these incidents resulted in
rapid death after dermal exposure to the heated liquid form of the chemical. This
report describes the five deaths associated with 2,4-DCP exposure (presented in the order
in which they were identified) and provides recommendations for preventing
additional deaths.

Case Reports

Case 1. On October 12, 1998, a29-year-old man employed at a Michigan
chemical company producing 2,4-D was sprayed with 2,4-DCP from a leak in tubing while
he was using steam to clear a blocked pump. The worker bypassed the nearest
safety shower and used a locker room shower, where he became unconscious.
Resuscitation attempts were unsuccessful, and the worker was pronounced dead at a hospital 1
hour after exposure. Skin surfaces exposed to 2,4-DCP included his forearms, right
knee, right thigh, and face. Except for chemical burns on his face and extremities
and pulmonary edema, the autopsy findings were unremarkable. 2,4-DCP was found in
his blood (7.2 mg/L free 2,4-DCP, 13.1 mg/L total 2,4-DCP) and urine (4.8 mg/L free
2,4-DCP, 6.2 mg/L total 2,4-DCP). Death was attributed to acute dichlorophenol intoxication.

Case 2. In 1991, a 33-year-old man working at a factory in France was
splattered over portions of his right thigh and arm with pure liquid 2,4-DCP while disposing
of industrial waste (1). He walked away from the scene and washed himself with
water without undressing. He experienced a seizure, collapsed within 20 minutes
of exposure, and died after unsuccessful attempts at resuscitation. 2,4-DCP was found
in his blood (24.3 mg/L), urine (5.3 mg/L), bile (18.7 mg/L), and stomach (1.2 mg/L).

Case 3. In September 1980, a 45-year-old man working at the same facility as
the decedent in case 1 sustained skin and upper-airway exposure after being sprayed
by steam containing 2,4-DCP. The worker bypassed the nearest safety shower,
started
decontamination using an unalarmed shower in a dressing area, and then moved to
an alarmed shower, which automatically notified emergency personnel and
summoned an ambulance. He sustained thermal burns to his skin, mouth, and upper airway,
lost consciousness, and died despite resuscitation attempts. An autopsy
revealed cutaneous burns on his neck, upper chest, back, and thighs; pulmonary
congestion with alveolar hemorrhage; and moderately severe hepatocellular fatty change.
His larynx was congested in a manner consistent with a steam/chemical burn, but
the trachea was un-remarkable, suggesting only upper airway exposure to the steam
and 2,4-DCP. No reliable data on 2,4-DCP concentration in biologic fluids were
available.* The final pathologic diagnosis was "acute steam and dichlorophenol exposure."

Case 4. In April 1992, a 64-year-old man at a chemical facility in England was
using steam to unblock a clogged pump carrying 2,4-DCP
(2,3). A pump seal failure allowed steam and 2,4-DCP to spurt onto his face and neck. Death occurred 20 minutes
after exposure.

Case 5. In April 1985, a 33-year-old man working at an Arkansas
manufacturing facility was splashed with a solution containing 51%
2,4-DCP while moving a hose used to transfer the material. The solution covered 60%--65% of his body surface
area (head, chest, neck, abdomen, arms, and thighs). When paramedics arrived, he
was unconscious and convulsing on the shower room floor. He was transported to
a hospital and pronounced dead approximately 90 minutes after exposure. An
autopsy revealed first-degree chemical burns on exposed skin surfaces; swollen, red,
sloughed mucosa of the larynx, trachea, and bronchi; focal hemorrhage and
considerable hemorrhagic frothy fluid in the lungs (with fluid extruding through his mouth
and nostrils); blue/tan swollen esophageal mucosa; and reddened mucosa and
turbid hemorrhagic fluid in the stomach. Microsections of the brain revealed
intense congestion and petechial hemorrhages. Serum total dichlorophenol concentration
at postmortem was 67 mg/L. The final pathologic diagnosis was "acute
chlorinated phenolic exposure and 60% chemical burns."

Reported by: Office of Pollution Prevention and Toxics, US Environmental Protection
Agency. Occupational Safety and Health Administration. Div of Surveillance, Hazard Evaluations, and
Field Studies, National Institute for Occupational Safety and Health, CDC.

Editorial Note:

2,4-DCP is a white solid at room temperature, but liquifies at 111
F--116 F (43 C--45 C). The liquid is rapidly absorbed through the skin. 2,4-DCP is not
believed to be used outside the chemical industry, although small amounts may be present
in drinking water when chlorination converts other phenolic compounds into
this chemical (4). An estimated 200 U.S. workers are potentially exposed to 2,4-DCP. As
of 1998, at least eight U.S. facilities were known to use or handle 2,4-DCP.
Annual worldwide production is estimated at 88 million pounds
(5). No OSHA, NIOSH, or American Conference of Governmental Industrial Hygienists exposure limits exist
for 2,4-DCP.

The mechanism by which 2,4-DCP causes death is uncertain, but this and
other chlorinated phenols are known to uncouple oxidative phosphorylation
(6). Most production of adenosine triphosphate, the carrier of free energy in cells,
occurs through oxidative phosphorylation. Uncoupling oxidative phosphorylation at
the
mitochondrial level leads to profound disturbance of energy production and may
have caused the rapid deaths described in this report. A characteristic sequence of signs
in animals given lethal doses of solid 2,4-DCP is consistent with the clinical
progression noted in these cases and includes tremors, muscle weakness, loss of
coordination, clonic convulsions, dyspnea, coma, and respiratory arrest
(4). Although three of the decedents in this report also were exposed to steam, the reported symptoms
and autopsy findings suggest that steam exposure did not play a substantial role in
these deaths. Finally, postmortem drug screens were negative in all five cases,
which excludes interaction with a drug or medication as a potential explanation for
the deaths.

Potentially exposed workers, their supervisors, and health and safety staff
should be aware of the hazards associated with exposure to 2,4-DCP, especially when
the chemical is in the liquid state. In an April 1999 letter and a February 2000
chemical advisory (7), EPA and OSHA notified facilities believed to use 2,4-DCP of these
fatalities and provided recommendations to prevent additional morbidity and
mortality. Standard safe work procedures should be developed and disseminated to
workers involved in tasks having potential 2,4-DCP exposure. Engineering controls and
source reduction methods should be adopted to eliminate the potential for exposure.
Detailed recommendations for appropriate protective clothing for dermal protection
and respirators for inhalation protection were specified in the EPA/OSHA
chemical advisory (7). Health and safety staff decontaminating exposed workers should
wear appropriate personal protective equipment and should participate in drills to
ensure proficiency while wearing this gear.

Any skin contact with liquid 2,4-DCP should be considered a
life-threatening medical emergency. Safety showers should be located in the immediate vicinity
of work areas having potential for 2,4-DCP exposure. These showers should be
alarmed so that assistance is summoned promptly. Exposed skin should be flushed for at
least 15 minutes, and contaminated clothing must be removed. Because 2,4-DCP
is lipophilic and has relatively low water solubility
(7), the use of water for skin flushing may lead to a protracted decontamination process. Additional research is needed
to identify more effective agents for skin decontamination. Treatment for
2,4-DCP intoxication is supportive, and there is no known antidote.

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